This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
檱 combines 木 (tree) with 箕, which likely contributes the sound. The exact historical development is uncertain.
A tree 木 beside a winnowing basket 箕. Without a clear meaning, picture an obscure wooden tool or a tree with basket-like leaves.
For キ, imagine a key キー made of wood from this mysterious tree: key -> キ.