SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a99f984c915475c1fa3613d9089a041b0ec54518031274b765fdd66290de04df' 
  AND token = 'wgaq4vJCIcC1gudnZijjc5q+xWdw3drqi4KuLM0y4uM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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