SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3574730e4048c0fcbd999394de82ce14ed6f749eb48853291e4c0f6f7a59321' 
  AND token = 'Kmgnrsb6pO7IU9J8o/+OgDn/gEELX2x5nNf9DbakWjU=' 
  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