SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ee586d53efa66add24823d1df354a4933edc77c2d37adfbcc4806fbffd2a564' 
  AND token = 'MCfAf72N1zBV39Q0WuT/fnbPSIb/mDyaaCJicqF2ILI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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