SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d37fd8a47c2fbf35b070a535b53786f0cae129c4c66119cf748251e5f1b1f6d' 
  AND token = 'ynrdUCwzZDvlUerd+B0obLOTwVNS2/e9fGWyqSfhUZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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