SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5f19624322dcf75a472c4f912b96077a71da367c8cf82ffff1c1e8cd80f17d7' 
  AND token = 'leupooWfLKvC7HKQWMpejxeYnqkPTCGSe7Z4OIi+7Ys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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