The optimization process and recommendations:

1. Avoid Selecting Unnecessary Columns (query line: 2): Avoid selecting all columns with the '*' wildcard, unless you intend to use them all. Selecting redundant columns may result in unnecessary performance degradation.
2. Avoid Subqueries (query line: 25): We advise against using subqueries as they are not optimized well by the optimizer. Therefore, it's recommended to join a newly created temporary table that holds the data, which also includes the relevant search index.
3. Create Optimal Indexes (modified query below): The recommended indexes are an integral part of this optimization effort and should be created before testing the execution duration of the optimized query.

Optimal indexes for this query:

ALTER TABLE `v_templates` ADD INDEX `v_templates_idx_id` (`id`);
ALTER TABLE `violations` ADD INDEX `violations_idx_id_v_id` (`id`,`v_template_id`);
ALTER TABLE `vnotices` ADD INDEX `vnotices_idx_v_datetime_vtemplate_id` (`v_notice_datetime`,`vtemplate_notice_id`);
ALTER TABLE `vnotices` ADD INDEX `vnotices_idx_vnotice_datetime` (`vnotice_datetime`);

The optimized query:

SELECT
        vtn.*,
        vn.v_notice_datetime 
    FROM
        v_templates vt 
    JOIN
        v_template_notices vtn 
            ON (
                vtn.v_template_id = vt.id
            ) 
    JOIN
        violations v 
            ON (
                v.v_template_id = vt.id
            ) 
    LEFT JOIN
        vnotices vn 
            ON (
                vn.vtemplate_notice_id = vtn.id
            ) 
    WHERE
        v.id = 1 
        AND vn.v_notice_datetime IS NULL 
        AND vtn.id > (
            SELECT
                max(vn.vtemplate_notice_id) 
            FROM
                vnotices vn 
            WHERE
                vn.vnotice_datetime IS NOT NULL
        )