If your luggage is locked and the country you are flying to doesn't have TSA master keys the security officials will cut-off your padlock just like any lock.
Travel Sentry Approved locks are now widely accepted in a many countries which have the TSA master keys. The list of countries continuously grows weekly. The list includes Canada, most of Europe, Japan, Australia, New Zealand, UAE, China, South Korea etc.
Security agencies in the list of countries below are equipped with master keys to allow them to open, inspect and re-lock luggage. This covers in excess of 650 airports.