SELECT 
  * 
FROM 
  cscart_mailing_lists 
  LEFT JOIN cscart_common_descriptions ON cscart_common_descriptions.object_id = cscart_mailing_lists.list_id 
  AND cscart_common_descriptions.object_holder = 'mailing_lists' 
  AND cscart_common_descriptions.lang_code = 'en' 
  INNER JOIN cscart_ult_objects_sharing ON (
    cscart_ult_objects_sharing.share_object_id = cscart_mailing_lists.list_id 
    AND cscart_ult_objects_sharing.share_company_id = 1 
    AND cscart_ult_objects_sharing.share_object_type = 'mailing_lists'
  ) 
WHERE 
  1 
  AND cscart_mailing_lists.status = 'A'

Query time 0.00058

JSON explain

{
  "query_block": {
    "select_id": 1,
    "const_condition": "1",
    "table": {
      "table_name": "cscart_mailing_lists",
      "access_type": "system",
      "possible_keys": ["PRIMARY"],
      "rows": 1,
      "filtered": 100
    },
    "table": {
      "table_name": "cscart_common_descriptions",
      "access_type": "const",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "107",
      "used_key_parts": ["object_id", "lang_code", "object_holder"],
      "ref": ["const", "const", "const"],
      "rows": 1,
      "filtered": 100
    },
    "table": {
      "table_name": "cscart_ult_objects_sharing",
      "access_type": "const",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "159",
      "used_key_parts": [
        "share_object_id",
        "share_company_id",
        "share_object_type"
      ],
      "ref": ["const", "const", "const"],
      "rows": 1,
      "filtered": 100,
      "using_index": true
    }
  }
}