SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1cb974a6e2e28bbac0b68affe2824ad66072acbe935b3816eb18712e9aa01c37' 
  AND token = '3VL9aMnRSbdAhnDJrvEJ3h1TERcyBnPbayLhUhP1F9o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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