Q: Is it mandatory for the tabernacle to remain locked outside of Mass? We have a beautiful tabernacle that was donated years ago. Unfortunately, it has a tricky, delicate lock that has been repaired several times at great expense. After the last repair (which took several months), it was decided to keep the key in the lock with written instructions below to guide the minister in opening/closing the door. (Right now the church itself is locked between Masses due to Covid-19.)
A: Holy Communion and Worship of the Eucharist Outside of Mass says in paragraph 10 that the eucharist is to be reserved in a tabernacle that is locked, and the one in charge is to ensure that the key is safeguarded.
I suppose if your church is kept locked, then you’re protecting the contents of the tabernacle, but at some point you’ll have to decide if the beauty of the tabernacle is worth the risk of vandals desecrating the eucharist.