SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55b55312aa48c0ca83aaf8e1e1cd4cd36fe1fce2421a8af540e2d5c617419fd8' 
  AND token = 'LHAUP1NJxFjJYSlidbEkPvfNngerKrsyqRr4yClAUgI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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