This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 槗 is uncertain. It visually contains 木 (tree) on the left, but the origin and function of the right component are unclear.
With no clear meaning, focus on the shape: a tree 木 beside a tall structure that looks like a bridge or framework. Remember it as a rare tree-related kanji.
For キョウ, imagine a rare tree named Kyo that grows beside a tall bridge-like structure: Kyo -> キョウ.