SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2cda80fd1bdd2268292af85bd20571999e65aa4907113c81a84c96d850bdc23' 
  AND token = 'a6Gj8elQ1smAl6TgqxQbmv+sXb0Upz3NvwKPZbxoVCg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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