Keys on blue lanyard with owl charm

I lost my keys yesterday around 3pm near the Cambridge Public Library on Broadway. The keys are on a bright blue nylon lanyard, with a silver house key, a black car key, and a small brass key with an enamel owl charm. There is also a tiny red tag labeled 'K-11' stuck on the ring. They are fairly worn but functional; the lanyard has a few frays near the clasp. This set is important to me - it's my only way into my apartment, and I really need it back as soon as possible.