SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '287d5f1859ad15c786755c794e7d364fea447a93049dfae7430508730a3a087d' 
  AND token = 'LgZpmAzTWad1ONsfAmz0AwiUtNmqv8a0IGKDo4hbk9Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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