SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35a827fd3bad7d8f8e947d983bc05d9f471eb99fbb4e8a124cd6684bdf347e02' 
  AND token = 'mB1FMq+zR+v6wl5Pt8JbPEJLZdDHis9JJZM0PqqiD4A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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