SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f2f48de80dfdaac2d0c9de7f91db8af70a468c5f990383aaadaf1911b158a7b4' 
  AND token = 'ch0SMd+3LgsgJy4HYVDWsbA3PskJjyi/FjgHcEo1Ros=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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