前辈写的 sql 语句如何优化

 select
        p.pr_id,  p.depot_id, p.depot_name, p.manager_user_id, p.manager_user_name,p.brand_id,p.brand_name,p.desc_id,p.desc_name,p.model_id,p.model_name,p.standard_repertory,
        p.prewarning_value,count(case when s.quality_id=1 then 1 end) as real_repertory,p.remark,p.create_emp,p.create_tm,p.update_emp,p.update_tm,p.apply_tm,p.notice_value, p.standard_mean_value, p.standard_adjust
       FROM
          `table1` p
        LEFT JOIN
        (select desc_id,model_id,brand_id,quality_id,depot_id from table2 where  sp_status_id in (1,2,8)) s
        ON  p.depot_id = s.depot_id
        and p.desc_id = s.desc_id
        and s.model_id in (SELECT g.model_id from table3 g where g.general_code=(SELECT o.general_code FROM table3 o where o.model_id=p.model_id))
        where 1=1
        <if test="depotId != null">
                and p.depot_id = #{depotId, jdbcType=INTEGER}
            </if>
            <if test="managerUserId != null">
                and p.manager_user_id = #{managerUserId, jdbcType=INTEGER}
            </if>
            <if test="descId != null">
                and p.desc_id = #{descId, jdbcType=INTEGER}
            </if>
            <if test="modelId != null">
                and p.model_id = #{modelId, jdbcType=INTEGER}
            </if>
            <if test="brandId != null">
                and p.brand_id = #{brandId, jdbcType=INTEGER}
            </if>
            <if test="managerUserName != null and managerUserName != ''">
                and p.manager_user_name = #{managerUserName, jdbcType=VARCHAR}
            </if>
            <if test="startTime != null">
                and p.apply_tm &gt;= #{startTime, jdbcType=TIMESTAMP}
            </if>
            <if test="endTime != null">
                and p.apply_tm &lt;= #{endTime, jdbcType=TIMESTAMP}
            </if>

           GROUP by p.pr_id having 1=1
           <if test="noticeType != null and noticeType ==1">
               and real_repertory &lt;= p.prewarning_value
           </if>
            <if test="realRepertory != null">
                and real_repertory=#{realRepertory, jdbcType=INTEGER}
            </if>

上一任开发者写了一个 sql 语句，我想优化一下，但是发现自己能力有限，谁可以帮个忙;
说说情况：

1. table1 表大概数据量只有 1000 条
2. table2 表的数据量大概有 100 万
3. table3 表大概只有 1000 条
   现在一次查询大概需要 2 分钟