SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad8627a9641b86edb6474f2f72c796554610ffc602511e90b387f11841d89959' 
  AND token = 'JVdaTQyWAqhzokbhUa8FpXzaU3nXC+RjOhydlKtFQPU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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