The ornamental design for a keyholder, as shown and described.
FIG. 1 is a top perspective view of a key holder, showing the new design with a door in an open position;
FIG. 2 is a bottom perspective view thereof, illustrated with the door in a closed position;
FIG. 3 is a front elevational view of FIG. 2;
FIG. 4 is a right-side elevational view of FIG. 2;
FIG. 5 is a left-side elevational view of FIG. 2;
FIG. 6 is a top plan view of FIG. 2;
FIG. 7 is a bottom plan view of FIG. 2; and,
FIG. 8 is a rear elevational view of FIG. 2.
The broken lines showing a set of keys in FIG. 1 are included for the purpose of illustrating the invention in use, and form no part of the claimed design.