Optimization paramters read-only mysql 5.7 database?

down vote favorite What’s the best way to MySQL database that is only read-only, and will never have any modifications made to it.

1) I have increased my innodb_buffer_pool_size to 70% of available RAM

2) Increase query cache size to 40mb

Running against a load generator, after some time the database starts bottlenecking to only 1000 statements per second.

The configuration is 2-cores, 8GB ram 50GB SSD. The database contains a single InnoDB 13 GB table with the same exact query running on two indexed columns.

We are using a vertx server to hit the database. The symptom we see is that the web service performance degrades after 15-20 minutes of heavy load.

Where can the bottleneck be? What parameters should we optimize?