SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9f038bd430ea726a8393137d1b8561ad35f279d85f7dd874beb9879970c7163' 
  AND token = 'VFE/RJDs5b5hRPmPQWSB24//IMP+vcMEowya1mUpPQE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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