Using INDEX and MATCH to find SUM

Hi all. Hope you're doing well.

I'm looking to find out how to use INDEX and MATCH in a way that will sum all the values in Column 2 IF the value in column 1 is equal to the value in cell R2C5. Column 1 will contain duplicate values, but it's corresponding value in Column 2 may vary. e.g. Column 1 contains the name of a county, column 2 contains the count of a specific building in that county. My formula wants to be able to figure out how many overall buildings there are.

With so many types of building (warehouse, store, residence, utility etc.) the whole array is very large and wanted a quick way to get the sum, if this is possible.

(numbers have been generated using RANDBTEWEEN 2,999 ;-))

Thank you.