used in place names, stratus
圛 is a rare kanji used mainly in place names, with a secondary meaning of stratus (a type of cloud). Its standalone meaning is unclear outside these specific uses.
圛 combines the enclosure 囗 (meaning boundary or enclosure) with 睪, which likely contributes a phonetic element. The exact historical development is uncertain, and the character is rare.
The outer 囗 is like a boundary, and inside is 睪, which looks like a tangle of lines. Imagine a place name on a map enclosed by a circle, with the tangled lines representing the winding paths or clouds (stratus) within that area.
For エキ, picture a place name sign with the kanji 圛, and a traveler saying 'Eh, key?' (エキ) as they try to find the right key to unlock the map to this obscure location.