SELECT 
  * 
FROM 
  cscart_bm_containers as c 
  LEFT JOIN cscart_bm_grids as g ON g.container_id = c.container_id 
WHERE 
  1 
  AND g.container_id IN (1, 2, 7, 4) 
ORDER BY 
  g.order, 
  g.parent_id, 
  g.grid_id ASC

Query time 0.00098

JSON explain

{
  "query_block": {
    "select_id": 1,
    "filesort": {
      "temporary_table": {
        "function": "buffer",
        "table": {
          "table_name": "c",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["container_id"],
          "rows": 4,
          "filtered": 100,
          "index_condition": "(c.container_id in (1,2,7,4))"
        },
        "table": {
          "table_name": "g",
          "access_type": "ref",
          "possible_keys": ["container_id"],
          "key": "container_id",
          "key_length": "3",
          "used_key_parts": ["container_id"],
          "ref": ["egkcysbp_cscartn.c.container_id"],
          "rows": 2,
          "filtered": 100
        }
      }
    }
  }
}