SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c08d29eb45725c91bfb6226e761fe908709fcc4300c30f168431400beecc376a' 
  AND token = '/lclgTBrAxtCVw/At2Bo46Lpn4EIsh9UMXnW8wCiR1M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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