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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '349ff643cd8a82810dc142859faaec154822a29af6e8431ee5deee272ea1f62f' 
  AND token = 'QEC6jz7UOVwg2mTigu2vaUKU0d9GWkShDFNjwVkiIa4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00010

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