Yes. Kevo Smart Lock does not require a data connection to lock/unlock with an Anytime eKey or a fob.
A data connection is required for initial account setup, signing into your Kevo account as well as Guest and Scheduled eKeys. Other features such as sending eKeys and receiving notifications will only work when you have a data connection. Connected cloud features, i.e. Honeywell Thermostat require a data connection, too.