Active/current (1-5%) and historical records in same table: index or partitioning?
Partitioning should work better than index if the number of rows is large. If the query needs to scan only one partition, it is more efficient than finding current rows through index. 

If SRC_CURRENT is updated to 0 when newer rows are loaded, you need to enable row movement for the table. This will allow rows to move from current partition to historical partition.

Alternatively, if current rows are always the most recent rows, you could range-partition the table by date. This would allow you to clear expired rows very fast by running drop partition for the oldest partition. This will also benefit queries against historical data that access a range of dates but not the whole history.