SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '59ccb4f21db12e7f9d5f004a9ae8c7f959af62d34a11a5f1ca50535432d66810' 
  AND token = 'O9/h39ikgLMd8jbFE7rSiQRg1+zu/LuDYiVqM/QpX/8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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