SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '535f4b7b6a9a97513585438887047f96461c5ff7caa0bb354c7e2777026b2528' 
  AND token = 'vydCzN515GTHNrtrhbMixoEG/2KGsTMzK4ZWQsT9DLI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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