SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a669ea45cb751ca9fecf86733dc439fb5e09947112dc54ff43dc47abb9f431ec' 
  AND token = 'XPQf+HjkLpKpSSMWA0lNEkCzkwsieGI8hM/h/dbhMyo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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