SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c8484a4b7c8a5c05ad928ae838d376b9bfc1ab5d17ddd55b4660d093b421c12' 
  AND token = 'ewXQEfOvy9uAHqf7aS7ATrA4mskry6CKTZqXuCYErSk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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