selection_id | group_id | selection_group_id |
------------------------------------------------
     1            1              1

selector_id | selection_id | name | index
------------------------------------------
     1             1         Step1   0
     2             1         Step2   1
     3             1         Step3   2

select selector_id
from selectors s
group by selector_id
having max(case when name = 'Step1' then 1 else 0 end) = 1 and
       max(case when name = 'Step2' then 1 else 0 end) = 1 and
       max(case when name = 'Step3' then 1 else 0 end) = 1 and
       max(case when name in ('Step1', 'Step2', 'Step3') then 0 else 1 end) = 0

select selector_id
from selectors s
group by selector_id
having count(distinct name) = 3 and
       max(case when name in ('Step1', 'Step2', 'Step3') then 0 else 1 end) = 0

SELECT selection_id, GROUP_CONCAT(name)
FROM selectors

SELECT DISTINCT Selection_ID
FROM (
  SELECT selection_id, GROUP_CONCAT(name) gc
  FROM selectors
  ) t
WHERE gc = 'Step1,Step2,Step3'

SELECT selections.selection_id FROM `prstshp_productsort_groups_selections` selections
WHERE EXISTS (SELECT * FROM  `prstshp_productsort_groups_selectors` s3
                WHERE s3.name = "Muskelaufbau" AND s3.index = 0 AND s3.selection_id = selections.selection_id)
AND
EXISTS (SELECT * FROM  `prstshp_productsort_groups_selectors` s4
                WHERE s4.name = "Mesomorph" AND s4.index = 1 AND s4.selection_id = selections.selection_id)
AND
EXISTS (SELECT * FROM  `prstshp_productsort_groups_selectors` s5
                WHERE s5.name = "Männlich" AND s5.index = 2 AND s5.selection_id = selections.selection_id)
AND
EXISTS (SELECT * FROM  `prstshp_productsort_groups_selectors` s6
                WHERE s6.name = "25-40" AND s6.index = 3 AND s6.selection_id = selections.selection_id)