SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fc31ffe2acdedece7d82c1eab79a8467a9263e40c5baaf12650ba30941ea555' 
  AND token = '77KZ4mFsjMP2gRjVdRhHiE2uDcsHL0lvZCFZv2UqwiU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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