SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    766, 767, 769, 749, 774, 779, 784, 785, 
    791, 795, 750, 751, 885, 810, 895
  )

Query time 0.00030

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_categories range parent parent 3 23 Using index condition

Result

category_id parent_id
769 749
784 749
785 749
795 749
885 749
766 750
767 750
774 750
791 750
810 750
895 750
779 751