SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b5b0f9db7e2a55b1bdd005fecd2b384a828dd81bfc68366c8ba2005e8caa3d8' 
  AND token = 'iS7XjxblUME0PVyU/3bfVOvNbf6wcy7MlizpKhPhAms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}