It makes no sense to go to the trouble of turning the five available keys simultaneously since they had to pick the locks for the two missing keys first anyway.
Travelling back to Portland from the Schwarzwald in Germany must have taken Nick and Monroe at least a day, half of which on a transatlantic flight. That is plenty of time to get Monroe's bite wound looked after. He could have gotten it disinfected and bandaged by a flight attendant while he had nothing else to do anyway.