SELECT 
  product_id, 
  amount 
FROM 
  cscart_warehouses_sum_products_amount 
WHERE 
  1 
  AND product_id IN (
    127, 51325, 63, 51326, 135, 50984, 51450, 
    51451, 51343, 51342, 51341, 51340, 
    47, 136, 65, 42, 51376, 51377, 51378, 
    51379, 51380, 134
  )

Query time 0.00046

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "27.11"
    },
    "table": {
      "table_name": "cscart_warehouses_sum_products_amount",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 48,
      "rows_produced_per_join": 48,
      "filtered": "100.00",
      "index_condition": "(`test_uchur_k`.`cscart_warehouses_sum_products_amount`.`product_id` in (127,51325,63,51326,135,50984,51450,51451,51343,51342,51341,51340,47,136,65,42,51376,51377,51378,51379,51380,134))",
      "cost_info": {
        "read_cost": "22.31",
        "eval_cost": "4.80",
        "prefix_cost": "27.11",
        "data_read_per_join": "768"
      },
      "used_columns": [
        "product_id",
        "amount"
      ]
    }
  }
}