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SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    814, 813, 998, 808, 999, 1000, 1001, 1002, 
    1009, 1003, 1004, 1005, 1006, 1007, 
    1008
  )

Query time 0.00029

Explain
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	cscart_categories	range	parent	parent	3		15	Using index condition