Simply tell the professor you are sorry and emphasize that you will try to make this a one-time occurrence. Honestly, it really doesn’t matter if you overslept or couldn’t find a parking spot. The long reasons why you were late are usually said in a way that makes you look irresponsible. Just get the information you need and move on.
If you know you’re going to be late in advance (e.g., you have a doctor appointment), it is courteous to email your professor before class. In your email, state when you expect to arrive, let the instructor know you will come in quietly and state that you will take responsibility for finding out what you missed