The maintenance person should not use his key to enter while you are in your apartment.

My manager will work with me as far as roughly scheduling a window of time that best works for me for maintenance to enter. For example, if I get notification that maintenance will be coming in 'Thursday', I can tell my manager that the ideal time for me would be between 2 and 4p.m. on Thursday and she will tell maintenance to knock on my door during that time only.