SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '466fe70a9d8cbd23f78a92c6da8c00a69bf053df5085b0cef9f435b362cf9f0e' 
  AND token = 'ZKtz888AdaCVgCxIm5v+ng+2sH3t7XmmVvQXOwfIzGM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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