SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '016b36837baa174dff4b4e501df951181df8c72823e47d90184690914be8443b' 
  AND token = '/5dIbQHyJvGuxZDTydymhDpaTXo4KLOV1BTI9KLBM2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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