SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb1c0a116ddea8e00b143dc130afd563de4a4ca8e5e21066b8a42d628cf7f552' 
  AND token = '6A3i+WOjYmi6NEqpAX3g6z3BF9lLcF9bhiSWvdz74ZA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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