SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83cd5cb39f41a9fbecc2f9c5c803d3bff8164cf28c638eaa7f06e09759ffa3e5' 
  AND token = 'JVBQvIsztKN+ecgHPZy/vbYKx+22SPfHdD/YbJ6yKV0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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