该sql加上limit 1 执行很慢

SELECT *
FROM t1
WHERE id = 999
AND (case $1
    WHEN 'true' THEN
    info = $2
    ELSE info = $3 end)

查看表结构

db=# \d t1
                            Table "public.t1"
  Column  |            Type             | Collation | Nullable | Default
----------+-----------------------------+-----------+----------+---------
 id       | integer                     |           |          |
 info     | text                        |           |          |
 crt_time | timestamp without time zone |           |          |
Indexes:
    "idx_t1" btree (info)

info上存在索引，且数据不重复。

不加limit的执行计划如下：

                                                   QUERY PLAN
----------------------------------------------------------------------------------------------------------------
 Limit  (cost=0.56..3.18 rows=1 width=45) (actual time=0.027..0.027 rows=0 loops=1)
   ->  Index Scan using idx_t1 on t1  (cost=0.56..3.18 rows=1 width=45) (actual time=0.025..0.026 rows=0 loops=1)
         Index Cond: (info = 'bill'::text)
         Filter: (id = 999)
 Planning Time: 0.158 ms