As a first step, you will probably want to create layers which show the MSA but only at points with a specific land use. This operation is called masking.

If you're using QGIS 3.22+, the simplest way to do this is using the raster calculator 'if()' function. The formula will look something like 

```
if("Land Use@1"=1,"MSA@1",-1)
```
This is a stab in the dark since don't know precisely your layer names or data types. It assumes Land Use has integer values and 1 is the land use value you are after in this masked copy. And it uses -1 as a fake NODATA value for MSA; you may need to change this. If you have QGIS <3.22, see https://gis.stackexchange.com/questions/110121/writing-conditional-statements-in-qgis-raster-calculator for how to fake it with multiplication and logical operators.

Then you need to tell QGIS -1 (or whatever) is NODATA value in the layer properties for the output layer.

You can then do any processing you need on each masked layer for each land use value.