SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57a06f7dcc36cde6c1373a5112470aa523a070a2c3729018248b83d2b583be4f' 
  AND token = 'oc2AWi5MzBw0mCjgAY/SVHyXbJ8sxUiGZQuqP19bJnM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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