SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84a265b920b7367dedccc4382b883e6daa94905f25e6ed21dbec2aa8ded9ddc2' 
  AND token = '4UwQl3ACGulA3EribjPcFfbN40HYB3bx8psKjtXylLA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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