SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7846551f157e437f305852bd85a4a088888eed0e46ddebb2c90362fdd4736a43' 
  AND token = 'wnPy13rDpP7ptpnZhOAgLRc17RVnX4eYSGGZItUiyLI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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