SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df57c91990e3d26af29c69cc00b4f1d5f693ebbcdd36be245869a9da31bade55' 
  AND token = 'vWW6IxJciRmRA9wHYkmjjD7uGVcX898Cihxsv1Hr6z4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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