SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fd8454908eecb50de51a5f644bbb5dec0ec291c7cfc75103703ce4be69580e2' 
  AND token = 'gdHbjqnG16AQGjj7++iRjai4/HOkbOuY4iRsOyIhaKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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