This video explains the basics of a key tool.
The key tool has also been referred to as a trunk key, used to access the trunk of a vehicle. You would hammer the flat end of the key tool into to key way, until it drives the lock cylinder inside. Then you would use the 90 degree bend to hook the lock mechanism to release the trunk. A lot of newer vehicles don’t have a key way into their trunk… and the 2 vehicles I have tried this technique on, it did not work because there was a guard blocking the key tool from hitting the locking mechanism.