Talk now invites a soul match to a call right now, instead of booking a time. The invitation always carries a Quest, so there is something to explore the moment you connect, and if your match accepts, the call is joinable straight away.
It expires after 15 minutes if it is not accepted. An invitation for this moment, not a booking.
If you would rather plan ahead, propose a time instead. Scheduled proposals stay open much longer and come with reminders.