your expression is valid and should indeed return a binary raster with 0 and 1. I've checked in QGIS 3.2.3 and it worked fine with a 4 band integer raster as input.
You probably did, but the first thing to check is that your raster calculator really failed. It is quite large so maybe the statistics are simply not up to date.
Also, because of the size, there could be a memory issue. So you should test on a small subset to make sure that this is not the problem.
If you installed QGIS with the OTB application, a workaround could be to use OTB's BandMath. the expression would then be
and you can use an extended filename for the processing of large images
Another alternative is to use the gdal raster calculator (processing toolbox > raster miscellaneous > Raster calculator). Then you select the raster and its first band as A, and you can use an expression like below:
gdal_calc --calc "A==4" --format GTiff --type Byte -A input.tif --A_band 1 --outfile OUTPUT.tif -co COMPRESS=LZW -co TILED=YES -co BIGTIFF=YES