SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '437a3b9528253b4c6cdb4ef21e2e6b4257e88160525f988570a07c4bfe7cc442' 
  AND token = 'QNpFaPWmRnTnQ9il+rMhhmt04Lqt0v+CVIgzkTODj/M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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