SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '38c959efc103aea69ef29da830b3c7250995ab05d028fb7678e13bc46870260b' 
  AND token = '6d+k6WWmDZ9Tgsn/0G2QtoNSy4hjX751YjwwNYBjv9M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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