SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    421303, 403435, 431792, 437499, 406022, 
    408527, 408919, 416225, 410745, 454746, 
    401209, 414316
  )

Query time 0.00047

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.0216566,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_products",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "loops": 1,
          "rows": 12,
          "cost": 0.0216566,
          "filtered": 100,
          "attached_condition": "cscart_products.product_id in (421303,403435,431792,437499,406022,408527,408919,416225,410745,454746,401209,414316)"
        }
      }
    ]
  }
}