The ornamental design for a mousekitchentimer, as shown and described.
FIG. 1 is a front view of the mouse kitchen timer showing our design;
FIG. 2 is a rear view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof; and,
FIG. 7 is a top, right front perspective view thereof.
The minute and numeral designations depicted by broken lines in FIGS. 1 through 4 and 7 have been shown for the purpose of illustrating features that form no part of the claimed design.