SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b8c081d6e25b99e2daddabf49389656e2bb507eeff35b64c060956c873c7c5b' 
  AND token = 'GhAeKRMuuj7YFkVYmA/DeVndaINq08WMnr8vv+zsw18=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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