It definitely is up to how you interpret the time.
One of possible scenarios I could make up is literally – when a token must last from some particular point in time til another point in time.
Say, you’re selling some API or resource. And a client purchased access that lasts for one hour and the access starts tomorrow in the midday.
So you issue a JWT with:
iatset to nownbfset to tomorrow 12:00pmexpset to tomorrow 1:00pm