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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '547735cb029bbde6dc9ba3ee319f620152df78cbd1da9a7a8382301ff802b3d1' 
  AND token = '/7tidFz26aO9tGWrSHKQbjONnn6NqlvsxoYhOjnPfnY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

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