SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87225f73765b4574a0ac1436edc5603eceef43acf089dc4912d143a0033dce13' 
  AND token = 'oMKzFV9GSznodVccRS4oFTrT5FknPRsBa5poU9GKzpk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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