[{email:"kate@example.com",password:"password_hash",birthday:"1956-09-05"},{email:"kate@example.com",password:"password_hash",birthday:"1992-03-12"},{email:"kali@example.com",password:"password_hash",birthday:"1993-03-12"},{email:"john@example.com",password:"password_hash",birthday:"1943-03-12"}]

db.collection.aggregate([{$match:{$expr:{$gt:[{$let:{vars:{diff:{$subtract:[new Date(),{"$toDate":"$birthday"}]}},in:{$divide:["$$diff",{$multiply:[365,24,60,60,1000]}]}}},65]}}},])