SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '836915b3cb829c57039b4d2c856d9e80fb549c468597664333aba4b9e159e533' 
  AND token = '+0u9nVtNpaGbKYS83B75FaFd0kKRVD1zyCGyoGpSj3o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}