SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b9a6c61a1386b232fc3b851360e22c632c1c87919434565ceaddf604fa486595' 
  AND token = 'EHWbQonoj5+HnW91AQzg1O+MwOA5MXFzVkB2aTgUPEA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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