SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '350a79c9fb351abcbf5099782832271a6c83eaa493783bc97aafe0660c120721' 
  AND token = 'vP0bLKZDEALyC0MIQI8xtOSuEat4iPY7qewuZQjMqMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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