SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c9cf4a75d839639c7bb1f4fe44736a1938d7ffcea975719c9750204eeccbdda' 
  AND token = 'NW7yoJ3SsZxezhTaXGSXYNi4b7tZMXd1XqKyoyDeyNo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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