SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2539a6dc3b92d63eb2be8ca42824834caf430d37378c35785708a332db56356f' 
  AND token = 'TrjeldHc/MwsCQEUVeZerqCFQNnkvMd0NlG1CMDD4yM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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