SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc36c0ec19caf57985e737d1414bbf0c3386cc659aca31d994def20760162c22' 
  AND token = 'QEc2BCADCj+T642kSIwddUe1g3WEFb1oBISqfOyge6k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}