SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73d0fd8308992f89b08334d23c01bbd84ee573ede572caebd44f0d5a13d7b97c' 
  AND token = '/vR3o1tgHKxJybglMnIdualzm+eioAu58SuNCUZU5oE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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