A key safe is by no means safe. With a simple manipulation of the mechanics inside, you can get access to their contents within a couple of minutes.
The key safe outside my flat is a very popular make based on a generic design from some Chinese company. By applying pressure to the release button and cycling through the keys, the correct buttons will either make a loud click when you press them, or you will feel resistance half way as you push down on it. The incorrect buttons will either not move at all, or will push down all the way without a click or any resistance half way down.
Once you have got all the numbers, click the clear switch, and then type them in. Due to the design of these safes, you dont need to enter them in any particular order. Once entered, you should be able to open it..!