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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab6547c671ff131ecbb56b903c4c58c64e185f143e1e6ebb0030d12ce17ce51f' 
  AND token = 'oEuq5li3ZvFdgBv+8/rkIU+46Tq4RTY+/hwTFN2aq48=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

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