Run this query to check for a blocking transaction

show-blocking-transactions.sql

SELECT 
trx_w.trx_id AS waiting_trx_id, 
trx_w.trx_mysql_thread_id AS waiting_process_id, 
TIMESTAMPDIFF(SECOND, trx_w.trx_wait_started, CURRENT_TIMESTAMP) AS wait_time, 
trx_w.trx_query AS waiting_query, 
l.lock_table AS waiting_table_lock, 
trx_b.trx_id AS blocking_trx_id, 
trx_b.trx_mysql_thread_id AS blocking_process_id, 
CONCAT(pl.user, '@', pl.host) AS blocking_user,
pl.command,
pl.time,
IF(trx_b.trx_query IS NULL, 'Sleeping', trx_b.trx_query)  AS blocking_query 
FROM INFORMATION_SCHEMA.INNODB_LOCK_WAITS AS w INNER 
JOIN INFORMATION_SCHEMA.INNODB_TRX AS trx_b ON trx_b.trx_id = w.blocking_trx_id 
INNER JOIN INFORMATION_SCHEMA.INNODB_TRX AS trx_w ON trx_w.trx_id = w.requesting_trx_id 
INNER JOIN INFORMATION_SCHEMA.INNODB_LOCKS AS l ON w.requested_lock_id = l.lock_id 
LEFT JOIN INFORMATION_SCHEMA.PROCESSLIST AS pl ON pl.id = trx_b.trx_mysql_thread_id 
ORDER BY blocking_trx_id ASC LIMIT 5\G

Please note, this will throw 2 warnings:

mysql> SHOW WARNINGS;
+---------+------+-----------------------------------------------------------------------------------------------+
| Level   | Code | Message                                                                                       |
+---------+------+-----------------------------------------------------------------------------------------------+
| Warning | 1681 | 'INFORMATION_SCHEMA.INNODB_LOCK_WAITS' is deprecated and will be removed in a future release. |
| Warning | 1681 | 'INFORMATION_SCHEMA.INNODB_LOCKS' is deprecated and will be removed in a future release.      |
+---------+------+-----------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)

Which is expected. I will update this gist when they do eventually become deprecated.