ST_IsValid(g)

Checks whether a geometry is valid, as defined by the OGC
specification. ST_IsValid() returns 1 if the argument is a valid
geometry byte string and is geometrically valid, 0 if the argument is
not a valid geometry byte string or is not geometrically valid. If the
argument is NULL, the return value is NULL.

The only valid empty geometry is represented in the form of an empty
geometry collection value. ST_IsValid() returns 1 in this case.

ST_IsValid() works only for the Cartesian coordinate system and
requires a geometry argument with an SRID of 0. An ER_WRONG_ARGUMENTS
error occurs otherwise.

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

