SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2872a8d886e3d9f1402aa1b2ba5fcc0354e1cde76de10569ceb998d563df3f55' 
  AND token = 'WjtsNnIzi0Hhm8K/tvZ410gK/zLWuIFY44EaCYTXauo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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