SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56629a92ce03a94e61d4ff397c6e457da1a2b46563d15bf23bcb28a097a12862' 
  AND token = 'OBlfzEevYOKH/gLhCnChENPr41WLBpsmLTodMfww+Xw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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