Hopefully it's one of those crappy locks where you can use a wave rake and not actually have to pick the damn thing. You would be surprised how often that works. I showed it off to my boss on one of our office doors and they ended up buying new locks after I opened it in like three seconds.
If they were able to lock it so quickly, it means it’s probably not a key-retaining lock, which means the locking pawls are spring-loaded, which means you can shim it.