SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc42acd6a14a7530338785fcda7a410ae9e8008df8d9acd2ad644bebfff60071' 
  AND token = '2FkzMKBNZTUz1Ih3fuqZgy8jvrme0wX9RkpXpAmZn20=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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