SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8998d56b11bb1ec7777dc21b0d13841192fe5cb088613d125de9837d702684c' 
  AND token = 'BlAHg2+FCLxKwbu2OxBGjP/BHq7HNl1V9Yc4TJa+XuE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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