This sounds like a job for the Geometry data type and spatial functions. The following query works for your example.
IF OBJECT_ID ('dbo.SpatialTable') IS NOT NULL
DROP TABLE dbo.SpatialTable;
GO
CREATE TABLE SpatialTable
(Cell CHAR(2),
GeomCol GEOMETRY);
GO
INSERT INTO SpatialTable (Cell, GeomCol)
VALUES ('A1', 'POLYGON ((0 0, 100 0, 100 100, 0 100, 0 0))');
GO
INSERT INTO SpatialTable (Cell, GeomCol)
VALUES ('A2', 'POLYGON ((101 0, 200 0, 200 100, 101 100, 101 0))');
GO
INSERT INTO SpatialTable (Cell, GeomCol)
VALUES ('B1', 'POLYGON ((0 101, 100 101, 100 200, 0 200, 0 101))');
GO
INSERT INTO SpatialTable (Cell, GeomCol)
VALUES ('B2', 'POLYGON ((101 101, 200 101, 200 200, 101 200, 101 101))');
GO
DECLARE @Point GEOMETRY;
SET @Point = 'POINT (25 130)'
SELECT
Cell
FROM
SpatialTable
WHERE
GeomCol.STIntersects(@Point) = 1;
SET @Point = 'POINT (105 40)'
SELECT
Cell
FROM
SpatialTable
WHERE
GeomCol.STIntersects(@Point) = 1;
