@Override
  public boolean shouldUseScanner(Scan scan, HStore store, long oldestUnexpiredTS) {
    // No optimizations implemented by default.
    return true;
  }
A "non-lazy" scanner which always does a real seek operation. Most scanners are inherited from
this class.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/NonLazyKeyValueScanner.java