SELECT 
  product_id, 
  amount 
FROM 
  cscart_warehouses_sum_products_amount 
WHERE 
  1 
  AND product_id IN (257, 135, 132, 134, 127, 260, 262)

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}