(The only reason these are the same question is for the pun. If they should be split, I can split them.)
Neither of these have tag wiki entries. As of now, lock has 182 questions, keys has 82.
lock has questions about a variety of topics, including screen locks, folders having a lock icon, APT being locked, etc. keys has questions about SSH key pairs, gnome keyring, media buttons on laptops, as well as general keyboard topics.
IMO, both of these should be removed. We have much better tags that can be used.