SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '500ae8873153022fdfcecdfc46eb636055bb3f25b5f04f56ce7179f79ecea60f' 
  AND token = 'tliot+yMBZgf4l58Mxq/CPJE0sHbl7pjRF6OFVK3Iyg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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