SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bdfb93f28a9249a29906539a6210c6b6b6dd237f11e64efe12bee14865a4f53b' 
  AND token = 'LZwGuOJas+HnRShedeDbWhU/pyc0/jPXKuBFHqq9RO0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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