SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bc42800859ad6c852dd3392074c6e55126d2770d4053b5a1a64bfc96c42347cd' 
  AND token = '5pnKwQnmlP/A8g0MzJuE/8sJ3suwq3mao0MtMxkdE4w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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