The ornamental design for a boat shaped keychain, as shown and described.
FIG. 1 is a perspective view of a boat shaped key chain; and
FIG. 2 is a top view of the boat shaped key chain;
FIG. 3 is a bottom view of the boat shaped key chain;
FIG. 4 is a front view of the boat shaped key chain;
FIG. 5 is a rear view of the boat shaped key chain; and,
FIG. 6 is a right hand side view of the boat shaped key chain.
The broken lines showing a key in FIGS. 1 to 5 are included only for the purpose of illustrating an environment and form not part of the claimed design.