And somewhere in the dark an insomniac locksmith weeps...

There are plenty 24 hour emergency locksmiths. In Canada at least.

Most locksmiths in the US have an emergency after-hours number to call that goes straight to their cell. They just charge extra for the inconvenience.

Or just call the boss?

You're correct. If op wasn't relived of their duties and allowed to go home, they must be paid for the time.

Or they could have called their manager to explain what happened and see what they recommend to do in the situation?

No engine braking though. Wouldn't want to wake the neighbors.

if you're going to brake why get the running start? If you meant break, I'm sure a heavy object in the store would work better.

But...the door is unlocked.

You could've just not say anything

he broke the key.

That's not automatically negligent; as long as they weren't doing anything silly with it, keys just break sometimes.

What if OP is a manager?

....then they call the emergency locksmith, get the lock fixed, and go home and sleep. :|

33, if OP is a manager, this wouldn't be the first time they're closing.

Maybe it was their first closing shift as a manager. Some places where I've worked, when someone was promoted to manager, they didn't close alone for a while until they were a little more experienced.

Yeah I hadn't considered that possibility, OP just sounded kinda junior. I'd expect a manager to be more confident dealing with something like this but you never can tell.

even if he's a manager there'll still be someone higher up to contact