SELECT 
  product_id, 
  is_stock_split_by_warehouses 
FROM 
  cscart_products 
WHERE 
  product_id IN (
    51084, 51094, 51104, 51211, 51210, 51222, 
    51257, 51258, 51292
  )

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "6.31"
    },
    "table": {
      "table_name": "cscart_products",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 9,
      "rows_produced_per_join": 9,
      "filtered": "100.00",
      "index_condition": "(`test_uchur_k`.`cscart_products`.`product_id` in (51084,51094,51104,51211,51210,51222,51257,51258,51292))",
      "cost_info": {
        "read_cost": "5.41",
        "eval_cost": "0.90",
        "prefix_cost": "6.31",
        "data_read_per_join": "96K"
      },
      "used_columns": [
        "product_id",
        "is_stock_split_by_warehouses"
      ]
    }
  }
}