SELECT 
  product_id, 
  amount 
FROM 
  cscart_warehouses_sum_products_amount 
WHERE 
  1 
  AND product_id IN (
    803, 802, 801, 800, 799, 798, 797, 796, 
    795, 792, 787, 786, 782, 819
  )

Query time 0.00013

JSON explain

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