This is a lock that I modeled that goes along with my Low Poly Key: https://www.cgtrader.com/free-3d-models/various/various-models/low-poly-key
Check out my page on itch.io: http://brainslugs83.itch.io/
Also this model is available in my open source UnityCommon package in the Models folder: https://github.com/BrainSlugs83/UnityCommon
If you use it in a project, leave a comment and let me know so I can check it out!