SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '278639d1545c02bf48d8c35d07397ce26f3fb325d5a54216b58718b716904a01' 
  AND token = 'vdFZYNjz+s6GZo3tyVIqwi10/3OxbV42rF5wggykTfM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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