SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ea3e7dda67438318dd970341776b4db6fb37b88268ff4fb8aa5476397400bbb6' 
  AND token = 'xE9iAjlSDrmi1lnIWfknktXoG4zMmw1up2VEy5TkYYQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

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