SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b16c30d23ac53b443367399bcd36f26af343c5dd0a6adebf3ac1bbdd7784edfc' 
  AND token = 'LZBq2qIFeFXAavJOUNpK/5LRciKTGTeGcwfNgLv/E8o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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