SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a94e4f0c65649e60da99bb739eef11e8e19269484848c7b8b7907f48c4e3980c' 
  AND token = 'mxBlY1GEdMzHpTr5E1/qdRmOSt1CphMihGRuDUAcQ4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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