SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    10596, 10597, 10598, 10599, 10600, 10521, 
    10520, 10519, 10517, 10516, 10515, 
    10514, 10513, 10512, 10511, 10510, 
    10509, 10508, 10507, 10506
  )

Query time 0.00059

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_products",
      "access_type": "range",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 20,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (10596,10597,10598,10599,10600,10521,10520,10519,10517,10516,10515,10514,10513,10512,10511,10510,10509,10508,10507,10506)"
    }
  }
}