Check if one MBR is covered by another. Returns 1 if the MBR of the first geometry is entirely contained within the MBR of the second geometry.
SET @g1a = ST_GeomFromText('Point(5 6)');
SET @g1b = ST_GeomFromText('Point(5 11)');
SET @g2 = ST_GeomFromText('Polygon((0 0,0 10,10 10,10 0,0 0))');
SELECT MBRCoveredby(@g1a,@g2), MBRCoveredby(@g1b,@g2);
+------------------------+------------------------+
| MBRCoveredby(@g1a,@g2) | MBRCoveredby(@g1b,@g2) |
+------------------------+------------------------+
| 1 | 0 |
+------------------------+------------------------+