SELECT 
  product_id, 
  amount 
FROM 
  cscart_warehouses_sum_products_amount 
WHERE 
  1 
  AND product_id IN (
    19390, 19391, 16954, 8125, 8126, 7969, 
    8357, 8299, 8879, 8358, 7451, 8671, 
    8242, 8124, 8239, 8376, 8814, 8377, 
    8241, 12403, 8238, 8159, 8240, 8375
  )

Query time 0.00066

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": 26,
      "filtered": 100,
      "index_condition": "cscart_warehouses_sum_products_amount.product_id in (19390,19391,16954,8125,8126,7969,8357,8299,8879,8358,7451,8671,8242,8124,8239,8376,8814,8377,8241,12403,8238,8159,8240,8375)"
    }
  }
}