Have you heard of this amazing dry lubricant called graphite? It works great for some specific uses such as violin strings and heavy hinges on vault doors. It is a good product for these applications because it reduces friction between the contact surfaces and any excess is able to fall away through the large opening.
Conversely, a closed area with tight clearance like the inside of a door lock is a very bad application for this powder-like dry lubricant. Applying graphite powder to a door lock will likely cause the small parts inside to grind as the powder begins to fill the small gaps. Further applications will eventually fill all remaining gaps effectively jamming the lock. Add a wet or humid environment and you basically turned the inside of your lock into a rock.
Once jammed and locked you will likely need a professional to come out and open and get the lock back in working order. Save yourself some trouble and avoid using graphite powder as a lock lubricant. I recommend using Houdini to lubricate your locks instead.