SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bbc31be6bb8da6dea39d8d48be95975bf60bbb27caa51f1591f579f17d7615c8' 
  AND token = 'srvlFwZ6S+TXm2LvbQa8jz3YxWyI2PONwJVZgi42xtE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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