我的MariaDB慢查询日志显示了下面的很多。

Time: 221202 11:46:57
Query_time: 5.022055  Lock_time: 0.000082  Rows_sent: 5  Rows_examined: 447119
Rows_affected: 0  Bytes_sent: 141
SELECT SQL_CALC_FOUND_ROWS  ab_posts.ID
                    FROM ab_posts  LEFT JOIN ab_postmeta ON ( ab_posts.ID = ab_postmeta.post_id AND ab_postmeta.meta_key = 'cid' )  LEFT JOIN ab_postmeta AS mt1 ON ( ab_posts.ID = mt1.post_id )
                    WHERE 1=1  AND ( 
  ab_postmeta.post_id IS NULL 
  AND 
  mt1.meta_key = '_json_file'
) AND ab_posts.post_type = 'listings' AND ((ab_posts.post_status = 'publish'))
                    GROUP BY ab_posts.ID
                    ORDER BY ab_posts.post_date DESC
                    LIMIT 0, 5;

如何加快查询速度？是否应该创建索引来加快查询速度？
UPDATE：下面是两个表的EXPLAIN查询和索引- ab_post_ meta和ab_posts

更新：我想我找到了源代码。查询是由WordPress核心文件wp-includes\class-wp-query.php生成的

$found_rows = '';
    if ( ! $q['no_found_rows'] && ! empty( $limits ) ) {
        $found_rows = 'SQL_CALC_FOUND_ROWS';
    }

    $old_request = "
        SELECT $found_rows $distinct $fields
        FROM {$wpdb->posts} $join
        WHERE 1=1 $where
        $groupby
        $orderby
        $limits
    ";