SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78b91bf3775cf52264c8c4c80498cb4a7ea81ee1b3eceb512452fe470c0e0bfd' 
  AND token = 'jTC/j8vG+uObzSw3/6yiJTKHoTN2BWUnD3cRidbUMZk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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