SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e528b98ef530fd5de4cdc53f7103048aa4bc3812cd297481caacbde152002647' 
  AND token = 'AH9i/+As866jlxg90JfxOvj7k/pY/nCMwpBkgqq8sH0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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