SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    1661, 255, 65, 1959, 1011, 1685, 1207, 
    1210, 1203, 1389, 1188, 1190
  )

Query time 0.00086

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 (1661,255,65,1959,1011,1685,1207,1210,1203,1389,1188,1190)"
    }
  }
}