SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bdb57da8cf072cd4724b6776399400f08ba286bbfad53435f4da204f9ec68c1c' 
  AND token = '93zfVwoA+EQny0S0U0qCMYlVtvfWnU59two4WmKrJ3Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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