SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f0cc57f8c4436005e3cf47b36d4a36e45c1bf29f7818826a06a88153811b4dc' 
  AND token = 'i74FWeMy0xkY+DveSg5JqkPlzwVnKxDKQ/LhnzlbKWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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