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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e999d68604de520af25e824f4904213a37c784d6c3051b18705a075024b80f08' 
  AND token = 'nDCu22nEizw59AMOFuJYH1x871jYaM2AgBWwWi5dsno=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

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