SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4bea0599fe5d5dd777585ae0b7a00675c89da14e16896c34db3af0055b783f45' 
  AND token = 'p6n8141kulSKJfjXbqK5pLW78CCeWN3o0yeH18QR+qo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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