A dead bolt with a keyed lock on the inside of an exterior residential door is prohibited. Yes it was permitted years ago and those older locks should be replaced. The locked door could pose a safety issue in an emergency. If the lock is locked and the key is removed there is no way to unlock and open the door and escape from the building quickly.
A knob on the inside and a key on the outside is correct.
It is illegal for a locksmith to install this type of lock on an exterior residential door.