I have received this email from Steam support.
There was an error with a recent Steam purchase.
We've saved your cart (including discounts) for 72 hours so you can attempt your purchase again.
If the cart has expired, can I still pay, if the payment method hasn't expired? The payment method involves scanning a barcode at a local shop, but gives several days.
So the barcode hasn't expired but the cart has. Can I still pay?