SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a99848197e546af721b88455b3962e94b494c305ad20323abfeab12ffb4da5af' 
  AND token = 'DdjOhChe74Tl81W0QRSqrvL4Lv/nQq7cJg3G0+a1lJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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