SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '791f75ae6323d9e021b47c19180a6d149b8331e231b2365e714977ee3b39b2e1' 
  AND token = 'gvBlQPDYnvPftBnZU6z4jKuXG81AHUWI7iZLm98VjdE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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