Kitchen receptacles can certainly be protected by a GFCI breaker.
The general answer to the access question can be found in the NEC 2017
210.8 Ground-Fault Circuit-Interrupter Protection for Personnel.
Ground-fault circuit-interrupter protection for personnel
shall be provided as required in 210.8(A) through (E). The
ground-fault circuit interrupter shall be installed in a readily
> accessible location.
Definition
Accessible, Readily (Readily Accessible). Capable of being
reached quickly for operation, renewal, or inspections without
requiring those to whom ready access is requisite to take
actions such as to use tools (other than keys), to climb over or
under, to remove obstacles, or to resort to portable ladders,
and so forth. (CMP-1)Informational Note: Use of keys is a common practice under
controlled or supervised conditions and a common alternative
to the ready access requirements under such supervised conditions
as provided elsewhere in the NEC.
So, in general, yes it can be in a locked room. It doesn’t fully answer your question as we would need to determine if the tenant is the person “to whom ready access is requisite”…
Who is responsible for ensuring a tripped GFCI device gets reset in a timely manner?