SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2dc9b9bf0315ca15a12f43ace309f7e3abf83414e0fa0bffe11365c778bc8542' 
  AND token = 'wr31R6sR6ABIwsySUGy7XUHceu7QWqlSomhaFnMYdMQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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