SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'afc112cb768e805ca072b3adb0346c9a67bd1ee8e17a69aeb2545f73026d41b2' 
  AND token = 'nj/mPchvy/ImZ6zEYOP2YXWnk8oUFqKVMlV0ZYMPM3g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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