SELECT 
  product_id, 
  amount 
FROM 
  cscart_warehouses_sum_products_amount 
WHERE 
  1 
  AND product_id IN (
    7913, 7914, 7232, 7763, 7374, 8829, 7779, 
    7804, 7915, 7905, 7237, 8053, 7452, 
    7906, 7916, 7917, 8388, 7780, 7377
  )

Query time 0.00059

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": 19,
      "filtered": 100,
      "index_condition": "cscart_warehouses_sum_products_amount.product_id in (7913,7914,7232,7763,7374,8829,7779,7804,7915,7905,7237,8053,7452,7906,7916,7917,8388,7780,7377)"
    }
  }
}