Where should I keep my tire lock key
In the glove compartment or in the trunk if so equipped.
FYI it is a colossal pain to replace those keys or remove a locking lug or rim without the original key, so wherever you put it make sure it is safe. Laying around loose in a dash compartment probably not a good idea for the long term. Get a box for it and make sure it is labeled.
Like by the spare tire