The ornamental design for a key slotrailcover, as shown and described.
FIG. 1 is a left elevation view of the key slot rail cover for use with a firearm key slot rail system;
FIG. 2 is a left side top rear perspective view of the key slot rail cover for use with a firearm key slot rail system;
FIG. 3 is a left side top front perspective view of the key slot rail cover for use with a firearm key slot rail system;
FIG. 4 is a right side top rear perspective view of the key slot rail cover for use with a firearm key slot rail system;
FIG. 5 is a front right elevation view of the key slot rail cover for use with a firearm key slot rail system;
FIG. 6 is a rear left elevation view of the key slot rail cover for use with a firearm key slot rail system; and,
FIG. 7 is a top side elevation view of the key slot rail cover for use with a firearm key slot rail system.
The broken lines shown in FIGS. 1-7 are included for the purpose of illustrating portions of the key slot rail cover that form no part of the claimed design.