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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '712456c088c7406770a4e95225da2c851abf6477c8cca253119ea464c20be899' 
  AND token = 'kmP1wCvAfBeY9SYOWVfXbB5DlwQTK6UaQxQL6rkB1VM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

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