SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ab706ccf6fee35688644b52847fe9cc322437237205d64d50254027b2ff3903' 
  AND token = 'xZsBLkZIZ8MhTx8d1TXaKmeqAzfwrCkYMLJsK7gC6rI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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