You can only follow the cable to find its source.
There is every chance it runs to a nearby socket which has become inaccessible when the kitchen cabinets were installed. This is a typical kitchen cowboy fitter trick.
DO NOT try to dismantle it without finding the source.
Two hints for tracing it:
Pull off the adjacent plinth panels to see if anything is revealed; they usually just clip to the cabinet legs.
Take out drawers and look if the back panels of the units finish short of the top. If you are really lucky a hidden socket may be there. If there is a gap but no socket then a mirror and torch may let you see something.