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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a648a7a1b94eaf33d84119f916a13ade3e50a8e075a0fcd0049ddeacd4f02e56' 
  AND token = 'Q+F2m0qob2LLZdY/ACoMtfEQQsH2+bHm+Y/spvPr4LM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

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