For Vostok, the controls were really not all that impressive by today's standards. The picture below shows the control and information panels on Vostok spacecraft.
Here, 1 is the information display (orientation, status lights, ...), 2 is a 2-axis joystick and 3 is the control panel. Quite ascetic, as you can see.
The lockout was electrical. You can clearly see it here in the top left corner:
And this picture shows the code lock part with its electrical connector:
Here, 1 is the encoder and 2 is the input area. The encoders were a separate, removable part and configured the code lock for a specific combination. They looked like this:
Now that is out of the way, what did the lockout actually do? When enabled, it electrically blocked any inputs from the control panel and all the work was done by the onboard computer. You can also see that some critical switches are even put being a clear cover (although that was not locked as far as I can see). The switches under that cover performed functions as:
- Enabling manual control (the joystick)
- Triggering the emergency signal
- Controlling the oxygen supply
After Vostok-2, the lockout was no longer used and the code lock was removed from the control panel. Most likely this happened after it was confirmed that the cosmonauts would not become delirious in space.
You can see a mock-up of the side panel here:
Source (in Russian)