SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    9788, 9790, 9791, 9792, 9795, 12561, 
    12560, 9683, 9685, 9686, 9687, 9688, 
    9689, 9690, 12544, 12546, 12547, 12548, 
    12549, 12550
  )

Query time 0.00070

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 (9788,9790,9791,9792,9795,12561,12560,9683,9685,9686,9687,9688,9689,9690,12544,12546,12547,12548,12549,12550)"
    }
  }
}