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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a12d1ad42583165c974e48bf786b93fee8faad55b36a2afabadfbb9a2cf526a' 
  AND token = 'iQ8vtPB7lPqCcBWrIjPQvTGxp00ZsTs1ZsO1SCNcEdI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

Explain
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE								Impossible WHERE noticed after reading const tables