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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76edf64a4d96b656673de3c1e00df5bbe558cc958493fe4530009c811e2a94c9' 
  AND token = '638UBGuFsufrfMeEYtggirs8xZZxdiL5csJYNOiJl9M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

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