Section 2 - Room door on the inside
The room door is a door. The room door is scenery. The room door is outside of Hotel room. Through it is the Upstairs corridor. The room door is open and unlocked.
Check locking the room door with the room key:
say "[We] would rather not lock [ourselves] in. With some bad luck the key might break inside the lock." instead. 
. The key can't fit two doors at the same time without extra extensions and this is such a minor detail that it's easiest to handle it by just blocking the action.