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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '261549f75fb185394e2f0b10f17e8d36bf4fefe991636849a9356f5ded3fe81a' 
  AND token = '79uRkVBvjCh2wOYOSB0xR67t0xvB4KGzlheO7M5MMvQ=' 
  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