SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98968b5baed4457de4e77b4648cc434eb878997fa550dd92d7bb9d85d6c63a9b' 
  AND token = 'PFTCLp07WQZrZuZUb5QKAknjhJvrkdsPb0lPerjD6GI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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