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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1678dd3c8b605de7e1ec042117fdda863319cc98a4e66676aceef868837bef37' 
  AND token = 'L6o0N33264UwPKzNE2bSgNZ2YbQ2G25vYQiiHeVki6Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

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