SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    9850, 9851, 9852, 9853, 9854, 9855, 9856, 
    9857, 9858, 9859, 9860, 9861, 9862, 
    9863, 9814, 9815, 9816, 9817, 9818, 
    9820
  )

Query time 0.00076

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 (9850,9851,9852,9853,9854,9855,9856,9857,9858,9859,9860,9861,9862,9863,9814,9815,9816,9817,9818,9820)"
    }
  }
}