SELECT 
  product_id, 
  amount 
FROM 
  cscart_warehouses_sum_products_amount 
WHERE 
  1 
  AND product_id IN (
    7408, 7778, 8845, 8846, 8548, 8880, 7399, 
    7412, 7625, 10247, 10248, 7410, 8090, 
    7409, 7154, 7155, 7411, 8091
  )

Query time 0.00181

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_warehouses_sum_products_amount",
      "access_type": "range",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 21,
      "filtered": 100,
      "index_condition": "cscart_warehouses_sum_products_amount.product_id in (7408,7778,8845,8846,8548,8880,7399,7412,7625,10247,10248,7410,8090,7409,7154,7155,7411,8091)"
    }
  }
}