SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88a4fb12046e67274ae2f9ac2e0ea65aef9b2a4e370468264361dec3d1e49984' 
  AND token = 'csRCWhhGoildoRKY9MfTrESIHYRkUZWqjGBGa+3xiB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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