SELECT 
  SQL_CALC_FOUND_ROWS (
    CASE WHEN products.parent_product_id <> 0 THEN products.parent_product_id ELSE products.product_id END
  ) AS product_id, 
  IF(
    shared_descr.product_id IS NOT NULL, 
    shared_descr.product, descr1.product
  ) as product, 
  IF(
    shared_prices.product_id IS NOT NULL, 
    MIN(
      IF (
        shared_prices.percentage_discount = 0, 
        shared_prices.price, 
        shared_prices.price - (
          shared_prices.price * shared_prices.percentage_discount
        ) / 100
      )
    ), 
    MIN(
      IF (
        prices.percentage_discount = 0, 
        prices.price, 
        prices.price - (
          prices.price * prices.percentage_discount
        ) / 100
      )
    )
  ) as price, 
  GROUP_CONCAT(
    products.product_id 
    ORDER BY 
      products.parent_product_id ASC, 
      products.product_id ASC
  ) AS product_ids, 
  GROUP_CONCAT(
    products.product_type 
    ORDER BY 
      products.parent_product_id ASC, 
      products.product_id ASC
  ) AS product_types, 
  GROUP_CONCAT(
    products.parent_product_id 
    ORDER BY 
      products.parent_product_id ASC, 
      products.product_id ASC
  ) AS parent_product_ids, 
  products.product_type, 
  products.parent_product_id 
FROM 
  cscart_products as products 
  LEFT JOIN cscart_product_descriptions as descr1 ON descr1.product_id = products.product_id 
  AND descr1.lang_code = 'en' 
  LEFT JOIN cscart_product_prices as prices ON prices.product_id = products.product_id 
  AND prices.lower_limit = 1 
  LEFT JOIN cscart_product_prices as prices_2 ON prices.product_id = prices_2.product_id 
  AND prices_2.lower_limit = 1 
  AND prices_2.price < prices.price 
  AND prices_2.usergroup_id IN (0, 0, 1) 
  INNER JOIN cscart_products_categories as products_categories ON products_categories.product_id = products.product_id 
  INNER JOIN cscart_categories ON cscart_categories.category_id = products_categories.category_id 
  AND (
    cscart_categories.usergroup_ids = '' 
    OR FIND_IN_SET(
      0, cscart_categories.usergroup_ids
    ) 
    OR FIND_IN_SET(
      1, cscart_categories.usergroup_ids
    )
  ) 
  AND cscart_categories.status IN ('A', 'H') 
  LEFT JOIN cscart_ult_product_descriptions shared_descr ON shared_descr.product_id = products.product_id 
  AND shared_descr.company_id = 1 
  AND shared_descr.lang_code = 'en' 
  LEFT JOIN cscart_ult_product_prices as shared_prices ON shared_prices.product_id = products.product_id 
  AND shared_prices.lower_limit = 1 
  AND shared_prices.usergroup_id IN (0, 0, 1) 
  AND shared_prices.company_id = 1 
  LEFT JOIN cscart_ult_product_prices as shared_prices_2 ON shared_prices.product_id = shared_prices_2.product_id 
  AND shared_prices_2.company_id = 1 
  AND shared_prices_2.lower_limit = 1 
  AND shared_prices_2.price < shared_prices.price 
  AND shared_prices_2.usergroup_id IN (0, 0, 1) 
WHERE 
  1 
  AND products.product_id NOT IN (297) 
  AND cscart_categories.company_id = 1 
  AND (
    prices.price >= 0.00 
    OR shared_prices.price >= 0.00
  ) 
  AND (
    prices.price <= 0.00 
    OR shared_prices.price <= 0.00
  ) 
  AND (
    products.usergroup_ids = '' 
    OR FIND_IN_SET(0, products.usergroup_ids) 
    OR FIND_IN_SET(1, products.usergroup_ids)
  ) 
  AND products.status IN ('A') 
  AND prices.usergroup_id IN (0, 0, 1) 
  AND prices_2.price IS NULL 
  AND shared_prices_2.price IS NULL 
GROUP BY 
  product_id 
ORDER BY 
  product asc, 
  products.product_id ASC 
LIMIT 
  0, 3

Query time 0.00317

JSON explain

{
  "query_block": {
    "select_id": 1,
    "filesort": {
      "temporary_table": {
        "function": "buffer",
        "table": {
          "table_name": "shared_descr",
          "access_type": "system",
          "possible_keys": ["PRIMARY", "product_id", "company_id"],
          "rows": 0,
          "filtered": 0,
          "const_row_not_found": true
        },
        "table": {
          "table_name": "shared_prices",
          "access_type": "system",
          "possible_keys": [
            "usergroup",
            "product_id",
            "company_id",
            "lower_limit",
            "usergroup_id"
          ],
          "rows": 0,
          "filtered": 0,
          "const_row_not_found": true
        },
        "table": {
          "table_name": "shared_prices_2",
          "access_type": "system",
          "possible_keys": [
            "usergroup",
            "product_id",
            "company_id",
            "lower_limit",
            "usergroup_id"
          ],
          "rows": 0,
          "filtered": 0,
          "const_row_not_found": true
        },
        "table": {
          "table_name": "prices",
          "access_type": "ALL",
          "possible_keys": [
            "usergroup",
            "product_id",
            "lower_limit",
            "usergroup_id"
          ],
          "rows": 12,
          "filtered": 91.667,
          "attached_condition": "((prices.lower_limit = 1) and (prices.product_id <> 297) and (prices.price >= 0.00) and (prices.price <= 0.00) and (prices.usergroup_id in (0,0,1)))"
        },
        "table": {
          "table_name": "products",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY", "status"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "ref": ["egkcysbp_cscartn.prices.product_id"],
          "rows": 1,
          "filtered": 100,
          "attached_condition": "(((products.usergroup_ids = '') or find_in_set(0,products.usergroup_ids) or find_in_set(1,products.usergroup_ids)) and (products.`status` = 'A'))"
        },
        "table": {
          "table_name": "descr1",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY", "product_id"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["product_id", "lang_code"],
          "ref": ["egkcysbp_cscartn.prices.product_id", "const"],
          "rows": 1,
          "filtered": 100,
          "attached_condition": "trigcond((descr1.lang_code = 'en'))"
        },
        "table": {
          "table_name": "prices_2",
          "access_type": "ref",
          "possible_keys": [
            "usergroup",
            "product_id",
            "lower_limit",
            "usergroup_id"
          ],
          "key": "usergroup",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "ref": ["egkcysbp_cscartn.prices.product_id"],
          "rows": 1,
          "filtered": 100,
          "attached_condition": "(trigcond(isnull(prices_2.price)) and trigcond(((prices_2.lower_limit = 1) and (prices_2.price < prices.price) and (prices_2.usergroup_id in (0,0,1)))))",
          "not_exists": true
        },
        "table": {
          "table_name": "products_categories",
          "access_type": "ref",
          "possible_keys": ["PRIMARY", "pt"],
          "key": "pt",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "ref": ["egkcysbp_cscartn.prices.product_id"],
          "rows": 1,
          "filtered": 100
        },
        "table": {
          "table_name": "cscart_categories",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY", "c_status", "p_category_id"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["category_id"],
          "ref": ["egkcysbp_cscartn.products_categories.category_id"],
          "rows": 1,
          "filtered": 100,
          "attached_condition": "((cscart_categories.company_id = 1) and ((cscart_categories.usergroup_ids = '') or find_in_set(0,cscart_categories.usergroup_ids) or find_in_set(1,cscart_categories.usergroup_ids)) and (cscart_categories.`status` in ('A','H')))"
        }
      }
    }
  }
}