Communicate how long login tokens are valid / Expire after first use

Currently, when logging in, a mail with a login token is sent. This token does however not expire when used once: When e.g. opening a private tab, the same token allows for another login, meaning it does not expire upon use. It would be best if every login token can only be used once.

When receiving a token, it would also be helpful to communicate for how long they are valid until they expire.