The prepared plan doesn't tell us where the time actually is spent. It's really just the graphical version of the explain plan.
Based on the numbers we see there, the result set that gets created is in the 700 millions, which clearly leads to the question: what do you want to do with the data?
Running this query every 5 minutes... what for?
The assumption that the more records you join the longer it might take is not wrong, but assuming a linear or worse growth of runtime with the growth of data is not appropriate.
Another important piece of the total query performance is that you are running in a scale-out scenario. Here table distribution can be critical as intra-node data transfer can take a long time.
The executed planviz will also shed light on this.
Finally, your SAP HANA version is ancient. SPS 11 is the current one and with SPS 8 you're missing out on a lot of optimizations that have been implemented since then.