Love locks, love-heart locks, wish locks, luck locks, and simply old-fashioned padlocks OH MY!
Using a padlock in a marriage ceremony is a symbolic gesture of everlasting love.
The story goes that once a couple close a padlock together, just as the lock cannot be unlocked, nor can their love and commitment to one another. If the padlock comes with a key, the key is tossed into a river (or ocean), or tied to a helium balloon and released during the wedding ceremony. This practice is particularly popular in Europe. No doubt, hundreds of keys have been tossed into the Rhine River once vows of eternal love have been exchanged. The tradition is spreading beyond Europe to bridges all over the world.
I'm sure you can do a symbolic tossing of the key to avoid problems with the authorities!