Opening a Door with a Key
Some scholars interpret seeing a door opened with a key as an answered prayer for the dreamer, their parents, or others. It may signify achieving one's desires and seeking assistance from others to reach goals. Opening a lock might also indicate relief and the removal of worries, while the lock itself could symbolize marriage or a guarantor.
Per Ibn Sirin's Muntakhab al-Kalam fi Tafsir al-Ahlam
Note: These are traditional scholarly interpretations (ijtihad) drawn from a specific classical source — not a binding religious ruling, fortune-telling, or a prediction of the future.