SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1725e68b5763b039d9652a0a5093141c6c0df258b235e4bdc56f78aea0af11e8' 
  AND token = 'ZR8NTzWtLsKmn++blId20H4T1UwQJjphYK6lB+txUsI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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