Although it’s an essential part of a householder’s range of tools, a stopcock key is unlikely to be used very often, so wear and tear ought to be minimal.
Make sure you get a zinc-plated key that is less likely to corrode if it gets wet. If it does get wet, wipe the key dry after use.
As it may lie idle for a long time, possibly several years, before it is used again, coating the key with light oil once in a while should further help to ensure it does not corrode.
