Depends on emphasis. Said with normal stress on the first syllable is “able to be unlocked”.

But if you pronounce it with extra emphasis on both of the first two syllables with a bit of a pause between, I think most people would think “not able to be locked”. Very context dependent though

Exactly. “Common sense” is belief or intuition pretending to be reason. Typically invoked when someone does truly believe something is true, but doesn’t have information or arguments to back it up.