这在ksql中目前是不可能的。
如您所见，您可以通过索引访问数组数据，具体如下：填充测试数据：

echo '{"id":1,"quux":[{"x":1,"y":2},{"x":3,"y":4},{"x":5,"y":6}]}' | \
kafkacat -b localhost:9092 -t quux

检查ksql中的消息：

ksql> print 'quux' from beginning;
Format:JSON
{"ROWTIME":1528791985250,"ROWKEY":"null","id":1,"quux":[{"x":1,"y":2},{"x":3,"y":4},{"x":5,"y":6}]}

创建流：

create stream mystream (id bigint, quux varchar) \
with (kafka_topic='quux', value_format='json');

查询流：

ksql> SET 'auto.offset.reset' = 'earliest';
Successfully changed local property 'auto.offset.reset' from 'earliest' to 'earliest'
ksql>
ksql> select * from mystream;
1528791985250 | null | 1 | [{"x":1,"y":2},{"x":3,"y":4},{"x":5,"y":6}]

创建流 array :

ksql> CREATE STREAM mystream2 (id bigint, quux array<varchar>) with (kafka_topic='quux', value_format='json');
 Message
----------------
 Stream created
----------------

按索引访问单个项目：

ksql> SELECT quux[0], EXTRACTJSONFIELD(quux[0],'$.x') AS X, EXTRACTJSONFIELD(quux[0],'$.y') AS Y from mystream2;
{"x":1,"y":2} | 1 | 2

但你要找的是 EXPLODE 函数，它在ksql中还不存在。
相关github问题：
https://github.com/confluentinc/ksql/issues/1324
https://github.com/confluentinc/ksql/issues/527
https://github.com/confluentinc/ksql/issues/1413 （我刚刚看到你已经登录了，谢谢你：）