Logging out / locking user

In the front of house, our CA's are often moving around and not tied to a specific computer terminal. This often results in one CA using another CA's account as its logged in and logging in takes time entering a long email and password (we turn off saved passwords for security) - Would there be any easy was to add a function to make it easier for users to jump on and off terminals under their own account and be logged out effectively when walk away? - I guess I am thinking of like in some restaurants when then present a tag or swipe their waitress card on a till to place the order or take payment. Maybe however something simpler like could both users login but then have a short pin code to switch to their account while logged in, automatically locking the screen after X mins inactivity or by button press if walking away???