Read your lease. If your lease allows your landlord to follow a lockout procedure, then your landlord can follow that procedure when you fail to pay your rent in full and on time. The idea is to get the delinquent tenant to contact the landlord, and perhaps to come to an agreement about the delinquent rent and when it will be paid.

Lockout is not the same thing as eviction. Your landlord must give advance notice of the lockout (which has apparently been given), providing at least five calendar days notice of the lockout. If you continue to fail to pay your rent, as long as the lockout process is authorized by the lease and the action is consistent with the notice, the landlord may lock you out of your unit and require you to request a key to regain entry. The key must be given upon request, and you do not have to pay additional rent in order to regain access to your rental unit.