Filesort
+- TEMPORARY
   table          temporary(v,b,s,t)
   +- JOIN
      +- Filter with WHERE
      |  +- col2mark lookup
      |     +- Table
      |     |  table          t
      |     |  possible_keys  PRIMARY
      |     +- Unique index lookup
      |        key            t->PRIMARY
      |        possible_keys  PRIMARY
      |        key_len        4
      |        ref            project.s.col4_id
      |        rows           1
      +- JOIN
         +- col2mark lookup
         |  +- Table
         |  |  table          s
         |  |  possible_keys  unique_col4_col1,site_col3_col1_id,site_col3_col4_id,col1_id
         |  +- Index lookup
         |     key            s->col1_id
         |     possible_keys  unique_col4_col1,site_col3_col1_id,site_col3_col4_id,col1_id
         |     key_len        4
         |     ref            project.v.id
         |     rows           11
         +- JOIN
            +- Filter with WHERE
            |  +- col2mark lookup
            |     +- Table
            |     |  table          b
            |     |  possible_keys  PRIMARY
            |     +- Unique index lookup
            |        key            b->PRIMARY
            |        possible_keys  PRIMARY
            |        key_len        4
            |        ref            project.v.col2_id
            |        rows           1
            +- col2mark lookup
               +- Table
               |  table          v
               |  possible_keys  PRIMARY,col2_id,col2_idcol1,col5,col2_ids
               +- Index lookup
                  key            v->col5
                  possible_keys  PRIMARY,col2_id,col2_idcol1,col5,col2_ids
                  key_len        4
                  ref            const
                  rows           1494