SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '159cd7f59e610fcc22dbfc9548be572599c2fcd462ada8713040bbdf198cdc8b' 
  AND token = 'kyRBZtSQLcvXNskzsKp+T6Eu3Ns0BjMIXnrWJ6sJtkw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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