SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e968fdfda20e685e5c3a34651449ff21b2d3b0a1a1d66f14ca0a3cec1ade82b9' 
  AND token = 'Lgtf18tunk3iPFZaerme1wOvtAUT7+pXyN0qHZbYfwY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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