SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfd638868bb622388c94e3f0e608e43237e76f7cf9769831f211375afd71a7b4' 
  AND token = 'KrGgpqM0b9+dZIVJPATBdRQp3UDQB6tfGoR7P/5Hsvs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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