SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f68354e5f1bd56d20dc75f4d8596c8d9cb6c92566d2dff6930e43d0c4aba0878' 
  AND token = 'w7KnlMWpDwBZy6y5NJKs4kzelArCkPukXZkeu69B5dI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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