How does object locking impact object workflows?

When you create an object workflow for an object that's not currently locked, a lock is created for that object.

You can create a new object workflow for a locked object in the sandbox that holds the lock. However, an object locked in a different sandbox is disabled for selection in Application Composer's list of available objects while creating an object workflow. Hover over the name of the disabled object in the list to identify which sandbox has a lock on that object.