TiDB查询使用limit,会有优化效果吗,发现使用limit之后,还是扫描了非常多的key

CREATE TABLE xxxxxx (
id bigint(20) NOT NULL AUTO_INCREMENT COMMENT ‘id’,
uid bigint(20) NOT NULL DEFAULT ‘0’ COMMENT ‘xx’,
people_task_id int(11) NOT NULL DEFAULT ‘0’ COMMENT ‘xx’,
task_group_id int(11) NOT NULL DEFAULT ‘0’ COMMENT ‘xx’,
task_id int(11) NOT NULL DEFAULT ‘0’ COMMENT ‘xx’,
sub_task_id int(11) NOT NULL DEFAULT ‘0’ COMMENT ‘xx’,
sub_task_type int(11) NOT NULL DEFAULT ‘0’ COMMENT ‘xx’,
cycle_id int(11) NOT NULL DEFAULT ‘0’ COMMENT ‘xx’,
progress_compute_end_time bigint(20) NOT NULL DEFAULT ‘0’ COMMENT ‘xx’,
next_compute_time bigint(20) NOT NULL DEFAULT ‘0’ COMMENT ‘xx’,
is_deleted tinyint(4) NOT NULL DEFAULT ‘0’ COMMENT ‘xx’,
ctime datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT ‘xx’,
mtime datetime NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT ‘xx’,
gid bigint(20) NOT NULL DEFAULT ‘0’ COMMENT ‘xx’,
crowd_dimension tinyint(4) NOT NULL DEFAULT ‘0’ COMMENT ‘xx’,
last_compute_time bigint(20) NOT NULL DEFAULT ‘0’ COMMENT ‘xx’,
PRIMARY KEY (id),
KEY idx_next_compute_time (next_compute_time),
KEY idx_progress_compute_end_time (progress_compute_end_time),
KEY idx_uid (uid),
KEY idx_people_task_id (people_task_id),
KEY idx_mtime (mtime),
UNIQUE KEY uk_uid_sub_task_id_cycle_id_gid (uid,sub_task_id,cycle_id,gid),
KEY idx_last_next_compute_time (last_compute_time,next_compute_time),
KEY idx_sub_task_type_last_next_compute_time (sub_task_type,last_compute_time,next_compute_time)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin AUTO_INCREMENT=14700001 COMMENT=‘xx’