Turning a key with arduino

Guys could you help me .how could I turn on aphysical door key with an Arduino and servos

Get one of these new doors that already has the mechanical end of that figured out, remove the electrical parts and replace with your own.

If working with an existing door and its lock, there is going to be a bit of work figuring out the mechanical end of it.

Jackmacerfy: how could I turn on aphysical door key with an Arduino and servos

How much torque does it take to turn the key? Can your servo generate that much torque?