Slow-running query on clustered MySQL environment
You may want to consider if you really need the MySQL Cluster, it may be overkill for your purposes and may not justify the complexity. A pair of MySQL Master-Master or Master-Slave instances with replication are good enough for many shops and will deliver better performance in this scenario. 

If you have to stay with your current architecture, you can add Index on column "somecol", first try HASH, then B-TREE index. These should help, still performance would not be as good as a simple host instance.