The ornamental design for a keyholder, as shown and described.
The claimed key holder is used to hold keys in readiness for their utilization. The claimed key holder can be stored in a pocket or purse when the keys are not in use.
FIG. 1 is a perspective view showing the front side and right edge thereof of a key holder having my new design;
FIG. 2 is a side view showing the front side of a key holder having my new design; and,
FIG. 3 is a side view showing the rear side of a key holder having my new design.