SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a76f74fff5d222265cd0f84c6e7be9503df219a4f82fb6619dc8a528ba87c96b' 
  AND token = 'Pb/f3u3GwbuZmpEwfZkGhr7OTHW7q4nuZBmmiK+zDXY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

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