SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17e9fd5852754822bf5d48fd4f1d4fc1bbe65692ea4b046bc93aa4aef171ee38' 
  AND token = '/3ZQLGgFr7P2BMEGvzvgt4urWyWAzaCT6lm+wJUaBgg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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