SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    1305, 1304, 1312, 1303, 1302, 1301, 1300, 
    1320, 1322, 1323, 1325, 1326
  )

Query time 0.00083

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": 12,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (1305,1304,1312,1303,1302,1301,1300,1320,1322,1323,1325,1326)"
    }
  }
}