SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20534819795185537722c82cd14c86a3f4b0f38a50096666d7e030f2b815d4e0' 
  AND token = '47nXoUyfMky+C/ITLwxjKhVDjk3SD09PWFAvdVJNtmI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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