SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '646e1cf61a94742ba7bb695c8554a2c8fe567ff733ac5132b5fb81c52379e29a' 
  AND token = 'gUnXPa5DLpflh2DB/Qu9KtGzRT83lTkJrbNZD5wVVT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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