code: public static boolean containsKeyColumn(KeyColumnValueStore store, StaticBuffer key, StaticBuffer column, StoreTransaction txh) throws BackendException {
          return get(store, key, column, txh) != null;
      }
docs: Returns true if the specified key-column pair exists in the store.
  
  @param store  Store
  @param key    Key
  @param column Column
  @param txh    Transaction
  @return TRUE, if key has at least one column-value pair, else FALSE