Anda memiliki tanda kurung yang hilang, Anda tidak menutup LineFromText Anda.
Coba:
SELECT *
FROM mytable
WHERE MBRContains(LineFromText(CONCAT(
'('
, @lon + 10 / ( 111.1 / cos(RADIANS(@lon)))
, ' '
, @lat + 10 / 111.1
, ','
, @lon - 10 / ( 111.1 / cos(RADIANS(@lat)))
, ' '
, @lat - 10 / 111.1
, ')' ))
,mypoint)