A padlock having a key intended to unlock another lock. The other lock can be a padlock or some other locking structure. The key is inserted into a bore made in the body of the padlock, intended for one end of the shackle. To fit the key into the bore, its blade section is pivotable relative the shank of the key, and the blade section is adapted, in a first position of the blade section, to be at least partially received into the bore. The shank of the key can be received into the bore as well.