

If it’s a double cylinder knob or handleset, i.e. keyed on both sides, you can indeed close the door with the mechanism in the locked position. This would obviously be impossible with a deadbolt.
Those are quite rare these days because they have the potential for the exact same failure mode as what has happened to OP. Typically you only find them in commercial settings, and I’ll bet you a nickel you’ll get flagged on your fire inspection if there is not another means of egress from the building. I don’t know where they’re located but I’ll further raise you a dime having the door arranged this way is illegal in their locale.
In a normal house you could just use another door. Unless he has a balcony and rappelling equipment (or a ground floor balcony), it’s unlikely OP has such a luxury.
I’d be concerned about some joker coming by and swiping the keys in the meantime, though.
If you include his going around the long way in the professor’s time machine and completely looping the time span of the universe in the process, then he’s probably second, but the oldest organic entity. He is his natural age plus 1000 years plus one universal lifetime. The professor is technically younger than him by nine hundred years and some change, and Bender is established to be young enough that Hermes approved his QC check. Those two being the only others to take the time machine trip with him.
Edit to add: And his Lars incarnation is even older still, having gone back to 1999 and living in “our” timeline, then freezing himself again.
Bender may have him beat by doing the universe loop plus getting stranded in Roswell and waiting out having his head getting dug up in the 3000’s. Possibly at least one of his time travel duplicates wound up even older still having used the universal time code to go steal ancient artifacts and wait with them in the cellar for thousands of years. But all of them blew up, and it’s not clear if any of those were the “prime” Bender or if the original Bender even survived and the current Bender is actually one of the duplicates…