SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b78f42aaf28c1909a4c776bc952c387259f03e7121de113f16d372eefa018dd' 
  AND token = 'SVfd5y1GBEgwTw7Bt+yxm/6fWhvvTtZB2onwLUxDTxw=' 
  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