Personally, I don't believe a lock is a good idea. I wouldn't do it, many reasons why but the main one would be I feel like it would create anxiety for the child. I would get a camera baby phone. Would that be a good option for you? Maybe put the lock on the bathroom door instead? And get a chain or something for the front door?
I feel the same as kaydee. I have a fear of being locked in, just the thought of it makes panic. If it is possible I would do what kaydee said lock the bathroom, put a chain on the front door ect. If you have no other option but to lock her door as long as it doesn't distress her it should be find and you shouldn't feel guilty. Its hard with your kid wants to get into everything. DD1 is always into everything every chance she get, I find it so tiring.