Generate many records.

generate_data.sql

DELIMITER $$
CREATE PROCEDURE generate_data()
BEGIN
  DECLARE i INT DEFAULT 1;
  DECLARE num_records INT DEFAULT 6000000;
  DECLARE hours_per_5_years INT DEFAULT 43800;
  DECLARE rand_time DATETIME;

  WHILE i < num_records DO
    SELECT NOW() - INTERVAL FLOOR(hours_per_5_years * RAND()) HOUR INTO rand_time;
    INSERT INTO outgoing_channels_conversions (id, account_id, text, comment_id, ticket_id, resource_type, created_at, updated_at) VALUES (i + 1000000, i, 'text', i, i, 'resource_type', rand_time, rand_time);
    SET i = i + 1;
  END WHILE;
END$$
DELIMITER ;

CALL generate_data();