insert between, chopsticks, divining sticks, plan
筴 centers on thin objects used for prying, picking, or planning: chopsticks that insert between food, divining sticks that select fates, and the idea of a plan as something inserted between present and future.
筴 combines 竹 (bamboo) with 夾 (insert between), suggesting bamboo objects used for inserting or picking. The exact historical development is uncertain, but the component relationship is clear.
Bamboo 竹 over 夾 (insert between) gives you thin bamboo tools that slip between things: chopsticks between food, divining sticks between fates, and a plan slipped between now and later.
For キョウ, picture using chopsticks to eat 今日 (きょう, today) lunch: きょう -> キョウ, and the chopsticks insert between the food.