SELECT
    filename,
    (stats).*
FROM (
    SELECT
        filename,
        ST_SummaryStats(
            ST_Clip(
                rast,
                1,
                ST_Buffer(
                    ST_SetSRID(
                        ST_Point(-90, 45),
                        4326
                    ),
                    1
                ),
                TRUE
            ),
            1,
            TRUE
        ) AS stats
    FROM
        rasters
    WHERE
        filename IN ('raster_grid_1_1_nodata.tif')
) AS stats_tbl;

SELECT
    (summarystats).*
FROM (
    SELECT
        ST_SummaryStats(
            ST_Clip(
                rast,
                1,
                CAST(
                    ST_Buffer(
                        CAST(
                            ST_SetSRID(
                                ST_Point(-90, 45),
                                4326
                            ) AS geography
                        ),
                        1000
                    ) AS geometry
                ),
                TRUE
            ),
            1,
            TRUE
        ) AS summarystats
    FROM
        rasters
    WHERE
        filename IN ('raster_grid_1_1_nodata.tif')
) AS summarystats_tbl;