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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21eb1359b0739dd925c9ee968a3e9a0b430d7b0a57cf0a4b5e95c2a47c628c05' 
  AND token = 'ZiDMrkdDrYrG/xiZ/Z5+kusSGhvnyuzoN4FDOZzy/7s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

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