SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56f878fbcf264b58942fc46adeca73dfc7d4ce4c9c15e113869177958896aafd' 
  AND token = 'Hq59ZGBNZUt8VAj6QCgPpptoe4OQVf1xDRJhj/aHZVw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}