ST_LongFromGeoHash(geohash_str)

Returns the longitude from a geohash string value, as a DOUBLE value in
the range [−180, 180]. The result is NULL if any argument is NULL. An
error occurs if the argument is invalid.

The remarks in the description of ST_LatFromGeoHash() regarding the
maximum number of characters processed from the geohash_str argument
also apply to ST_LongFromGeoHash().

URL: http://dev.mysql.com/doc/refman/5.7/en/spatial-geohash-functions.html

