SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd851edc8489116241c3633dc41abf56d88cf336b6126abb1084544f7e493ab04' 
  AND token = 'kynrA1TAUXgWsmshpzDaaJje7aGtmyJ3j3ZmDhB+r1w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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