SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '845b63168558bcd9826bcc1627ec334ed2938df6f15738bb7e7e43ab07dd6485' 
  AND token = 'prdZki11qjxB9GveWMNC6vni7tHEGAp12UrkgAM1SRk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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