SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '345e0d6a860cbd002d32620892eff77088781ec410213328964c0320370a8a87' 
  AND token = 'T+JVzjhHl0IRGLu1cGgFpopRyW+KlFoLufkilaKxWzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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