How to handle VirWox transfers and invoices that expire quickly? I would like to withdraw a moderate amount of Bitcoin (equivalent to a few tens of USD) to pay the subscription to an online service.

I tried to use the "Request Withdrawal" command on the VirWox site, but it resulted in a message notifying that the Bitcoin transactions are only processed after a 48 hours period.

The invoice provided by the online service I want to subscribe to becomes expired after 15 minutes ; at least it is what is displayed on the pay site page I was redirected to (bitpay.com).

Is it possible to proceed to such a transaction directly from VirWox ? Or should I consider an other method ?

Thanks in advance for all suggestions (also please excuse my inexperience about the subject).
AFAIK VirWox is an exchange. You're trying to use it as a wallet. Since it isn't built to be a wallet, you're experiencing difficulties.

Instead, withdraw your bitcoins to a wallet after buying them on VirWox. Then use your wallet to pay your invoice.

You can find an overview of wallets here: Choose your wallet