--------------------------------------------------------
-- Table
CREATE TABLE `tbl_test` (
  `entry_id` int NOT NULL,
  `dt_create` datetime NOT NULL,
  `cnt` int NOT NULL DEFAULT '0',
  `title` varchar(100) DEFAULT NULL,
  `cnt_update` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

-- Indexes
ALTER TABLE `tbl_test` ADD PRIMARY KEY (`entry_id`);
ALTER TABLE `tbl_test` MODIFY `entry_id` int NOT NULL AUTO_INCREMENT, AUTO_INCREMENT=4;

-- Data
INSERT INTO `tbl_test` (`entry_id`, `dt_create`, `cnt`, `title`, `cnt_update`) VALUES
(1, '2021-11-13 13:15:00', 0, 'aaa', '2021-11-13 21:16:00'),
(2, '2021-11-13 13:15:07', 0, 'bbb', '2021-11-13 21:16:07'),
(3, '2021-11-13 13:15:33', 0, 'ccc', '2021-11-13 21:16:33');

-- Copy `dt_create` to `cnt_update`
UPDATE `tbl_test` SET `cnt_update`=`dt_create` WHERE 1

-- Trigger
DROP TRIGGER IF EXISTS `before_cnt_update`;
DELIMITER --
CREATE TRIGGER `before_cnt_update` BEFORE UPDATE ON `tbl_test`
FOR EACH ROW BEGIN
    IF OLD.cnt < NEW.cnt THEN
        SET NEW.`cnt_update`=Now();
    END IF;
END
--

-- Find rows where `dt_create` <> `cnt_update`
SELECT * FROM `tbl_test` WHERE `cnt_update` <> `dt_create`